BIOLOGIST J

Evolvability: What kind of embryos (and their phenotypic traits) are more “evolvable” during evolution?

• What are the features of phenotypic traits that are more/less likely to change (evolve) during evolution?
• By identifying these, can we infer general laws that predict how embryonic development influences phenotypic evolution?

Can we investigate possible mechanisms of phenotypic evolution through comparing the genomes of different species?

• How did animals evolve to become what they look like today? What are the genetic bases of the evolution of their morphologies?
• What makes us human? Why do those 3 billion base pairs create a human body but not an elephant?

Physiology plays critical roles in maintaining organismal functions (such as through homeostasis), but what are their roles in developing embryos?

• Traditionally, developmental biology focuses on the formation of morphology, but how do physiological functions emerge during embryogenesis?
• Do physiological functions have any roles in ensuring morphogenesis can proceed normally?

Can we say which embryo(s) or developmental process(es) of which species is more/less evolutionarily derived?

• Distinguishing evolutionary conservation from derivedness
  – Jason Cheok Kuan Leong*, Masahiro Uesaka, Naoki Irie*
  – Life (2022)
  – Link to the paper　
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• Derivedness index for estimating degree of phenotypic evolution of embryos: a study of comparative transcriptomic analyses of chordates and echinoderms
  – Jason Cheok Kuan Leong*, (17 other co-authors), Naoki Irie*
  – Frontiers in Cell and Developmental Biology (2021)
  – Link to the paper　
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• Although echinoderms have often been considered as highly derived species because of their exceptional morphologies, their developmental processes do not seem to be much more highly derived than those of the sister groups (chordates).
• By contrast, vertebrate embryos appear to be highly derived.
• Through developing molecular methods that could potentially evaluate “derivedness” more appropriately, we also discussed the conceptual limitations in many currently used methods and suggested potential directions for future studies.

How did echinoderms evolve their fivefold symmetrical body plan from the bilateral ancestors?

• Genomic insights of body plan transitions from bilateral to pentameric symmetry in Echinoderms
  – Yongxin Li, (9 other co-authors), Jason Cheok Kuan Leong, (22 other co-authors), Wen Wang*, Naoki Irie*
  – Communications Biology (2020)
  – DOI: 10.1038/s42003-020-1091-1
  – Link to the paper　
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• Surprisingly, despite the exceptional morphologies of echinoderm species, not only their embryonic development but also their metamorphosis appear to utilize many genes that are involved in the formation of bilateral body plans.
• Our genomic analyses also indicate that there are not so many genes that are “special” to echinoderms (e.g. not so many echinoderm-specific gene families, etc.)